java NullPointerException MainFragment facebook登录
对这件事很陌生。我正在尝试让一个简单的facebook登录应用程序在登录后显示一些基本的用户详细信息。当我尝试运行该应用程序时，会收到消息“不幸的是，FacebookTest已停止”。我似乎得到了一个NullPointerException，但我一辈子都不知道为什么。以下是我的logcat输出：
03-25 12:01:16.850 919-919/com.example.robert.facebooktest E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.robert.facebooktest, PID: 919
java.lang.NullPointerException
at com.example.robert.facebooktest.MainFragment$2.onCompleted(MainFragment.java:87)
at com.facebook.Request$1.onCompleted(Request.java:283)
at com.facebook.Request$4.run(Request.java:1668)
at 安卓.os.Handler.handleCallback(Handler.java:733)
at 安卓.os.Handler.dispatchMessage(Handler.java:95)
at 安卓.os.Looper.loop(Looper.java:136)
at 安卓.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
我的代码如下：
主要活动。爪哇
package com.example.robert.facebooktest;
import 安卓.os.Bundle;
import 安卓.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity {
private MainFragment mainFragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
// Add the fragment on initial activity setup
mainFragment = new MainFragment();
getSupportFragmentManager().beginTransaction()
.add(安卓.R.id.content, mainFragment).commit();
} else {
// Or set the fragment from restored state info
mainFragment = (MainFragment) getSupportFragmentManager()
.findFragmentById(安卓.R.id.content);
}
}
}
主要片段。爪哇
package com.example.robert.facebooktest;
import 安卓.content.Intent;
import 安卓.os.Bundle;
import 安卓.support.v4.app.Fragment;
import 安卓.util.Log;
import 安卓.view.LayoutInflater;
import 安卓.view.View;
import 安卓.view.ViewGroup;
import 安卓.widget.TextView;
import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.UiLifecycleHelper;
import com.facebook.model.GraphUser;
import com.facebook.widget.LoginButton;
public class MainFragment extends Fragment {
TextView name;
TextView location;
TextView gender;
private static final String TAG = "MainFragment";
// Create, automatically open (if applicable), save, and restore the
// Active Session in a way that is similar to Android UI lifecycles.
private UiLifecycleHelper uiHelper;
private View otherView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// To maintain FB Login session
uiHelper = new UiLifecycleHelper(getActivity(), callback);
uiHelper.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_main, container, false);
// Looks for Login button
LoginButton authButton = (LoginButton) view.findViewById(R.id.authButton);
authButton.setFragment(this);
// Set View that should be visible after log-in invisible initially
otherView = view.findViewById(R.id.other_views);
otherView.setVisibility(View.GONE);
//authButton.setReadPermissions(Arrays.asList("user_likes", "user_status","email","user_birthday"));
return view;
}
// Called when session changes
private Session.StatusCallback callback = new Session.StatusCallback() {
@Override
public void call(Session session, SessionState state,
Exception exception) {
onSessionStateChange(session, state, exception);
}
};
// When session is changed, this method is called from callback method
private void onSessionStateChange(Session session, SessionState state,Exception exception) {
final TextView name = (TextView) getView().findViewById(R.id.name);
final TextView gender = (TextView) getView().findViewById(R.id.gender);
final TextView location = (TextView) getView().findViewById(R.id.location);
if (state.isOpened()) {
Log.i(TAG, "Logged in...");
// make request to the /me API to get Graph user
Request.newMeRequest(session, new Request.GraphUserCallback() {
// callback after Graph API response with user
// object
@Override
public void onCompleted(GraphUser user, Response response) {
if (user != null) {
// Set view visibility to true
otherView.setVisibility(View.VISIBLE);
// Set User name
name.setText("Hello " + user.getName());
// Set Gender
gender.setText("Your Gender: "
+ user.getProperty("gender").toString());
location.setText("Your Current Location: "
+ user.getLocation().getProperty("name").toString());
}else{
return;
}
}
}).executeAsync();
} else if (state.isClosed()) {
Log.i(TAG, "Logged out...");
otherView.setVisibility(View.GONE);
}
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
uiHelper.onActivityResult(requestCode, resultCode, data);
Log.i(TAG, "OnActivityResult...");
}
@Override
public void onResume() {
super.onResume();
uiHelper.onResume();
}
@Override
public void onPause() {
super.onPause();
uiHelper.onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
uiHelper.onDestroy();
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
uiHelper.onSaveInstanceState(outState);
}
}
主要活动。xml
<LinearLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
xmlns:tools="http://schemas.安卓.com/tools"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
安卓:background="@drawable/bg_gradient"
安卓:orientation="vertical"
安卓:paddingBottom="@dimen/activity_vertical_margin"
安卓:paddingLeft="@dimen/activity_horizontal_margin"
安卓:paddingRight="@dimen/activity_horizontal_margin"
安卓:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.robert.facebooktest.MainActivity" >
<ImageView
安卓:layout_width="300dp"
安卓:layout_height="100dp"
安卓:layout_gravity="center"
安卓:src="@drawable/voyager_logo" />
<LinearLayout
安卓:id="@+id/other_views"
安卓:layout_width="match_parent"
安卓:layout_height="0dp"
安卓:layout_weight="1"
安卓:orientation="vertical"
安卓:padding="5dp" >
<TextView
安卓:id="@+id/name"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_marginLeft="10dip"
安卓:gravity="left"
安卓:text="Name"
安卓:textColor="@color/white"
安卓:textSize="30dp" />
<TextView
安卓:id="@+id/gender"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_marginLeft="10dip"
安卓:gravity="left"
安卓:text="Gender"
安卓:textColor="@color/white"
安卓:textSize="15dp" />
<TextView
安卓:id="@+id/location"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_marginLeft="10dip"
安卓:gravity="left"
安卓:text="Location"
安卓:textColor="@color/white"
安卓:textSize="15dp" />
</LinearLayout>
<LinearLayout
安卓:id="@+id/fb_view"
安卓:layout_width="match_parent"
安卓:layout_height="0dp"
安卓:layout_weight="1"
安卓:gravity="bottom"
安卓:orientation="vertical"
安卓:padding="5dp" >
<com.facebook.widget.LoginButton
安卓:id="@+id/authButton"
安卓:layout_width="250dp"
安卓:layout_height="wrap_content"
安卓:layout_gravity="center_horizontal"
安卓:layout_marginTop="30dp" />
</LinearLayout>
# 1 楼答案
87号线到底是哪一条？在onCompleted（）中的某个地方